sorry for that beforehand, but yes, I’m another newbie using (or at
least trying to use) NGINX in a mail proxy setup.
I read the wiki entries and docs beforehand… and I thought it just
works like that (passing auth to backend).
So actually I was rather shocked that authentication is not passed to
backend SMTP servers opposed to POP and IMAP backends.
As for our deployment, it would be a pain in the arse to import login
data from our backend servers.

So research a bit and at least I’m not the only one trying to use a
setup like this.

David Jonas even wrote a patch addressing this issue.
But as we only use official distribution packets, and also his patch is
for a quite old nginx version, that won’t work for us.

Hence I kindly ask of you, also in the name of my predecessors and
everyone else looking for a solution like this, to implement a method
for passing smtp login information to the backend server in one of the
next versions.